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SSSD becomes unresponsive while continuing to run useradd continuously in batches.

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Operating System and Software

  • Rocky Linux 8
  • sssd
  • useradd

Problem

  • SSSD becomes unresponsive while continuing to run useradd continuously in batches.

    For example:

    # for i in `seq 1 4500` ; do useradd -s /sbin/nologin testuser$i ; done
    
  • The following error was frequently seen.

    The memcache was not invalidated by NSS responder.
    

How to Fix

To work around the problem, temporarily stop the sssd service between successive useradd runs.

# systemctl stop sssd

Origin of the Problem

The command useradd in Rocky Linux 8 executes the command sss_cache internally to clear the sssd cache.

If you run useradd continuously to create many users, sss_cache will also be executed each time, increasing the load on sssd backend processes such as sssd_be and sssd_nss, and adversely affecting sssd performance.

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